Used to Replace. Nickel-titanium Makes Excellent Parts for Humans

In Moscow, a correspondent asked questions; in the USA, Alexey Volynsky, professor from the University of South Florida was an interviewee. They talked about Tomsk. A well-known materials scientist found himself to become the leading foreign scientist involved in the MegaGrant from the Government of the Russian Federation, and in the summer, he worked in the laboratory of Tomsk State University, where promising titanium nickelide alloys are being developed. Alexey Alexandrovich is the author of more than 430 scientific papers, and his h-index is 46.

– How did you happen to become the research director of the laboratory at TSU?

“I have to start in a roundabout way. For many years, I have been participating in grant competitions for American students to travel abroad to exchange experiences. My team did research in laboratories in Europe and China. For example, in Dresden, we studied cracks in multilayer films. My colleague collaborates with Tomsk scientists. Last year, they told him that the laboratory of the State University, despite strong competition, won a large three-year grant from the Government of the Russian Federation. (There were only 43 grants of that kind throughout the country). Tomsk scientists tried to find a foreign materials scientist who, according to the MegaGrant terms, should lead the project. I took a chance and sent a letter to Tomsk, but I did not expect to succeed. When TSU announced that I was accepted as a leader of the project, I was pleasantly surprised. I will explain why.

I last visited Russia in 2010, taking advantage of an annual sabbatical. According to the rules of the University of South Florida, I can have it once every seven years. I flew to Moscow and decided that it would be nice to get a job there. It is of interest to me: I cooperate with scientists from different countries of the world, but not with Russian ones. Now, I finally have a chance to work with them. However, I was disappointed. On the recommendation, I came to one seemingly very solid institute with numerous laboratories. However, in reality, they turned out to be almost a fake for the most part. Another time, I met with the manager of a very large corporation. He looked through my resume and said: we have never had such specialists and do not need to. I stopped my attempts to get employed in the capital. Now, years later, a great opportunity has opened up to work in Tomsk for several years. According to the grant terms, I have to stay in Russia for 90 days a year, which I found perfect: the university in Florida pays me a salary for only nine months, the rest of the time I have to live on grants. This is the practice of American universities. I am happy that my knowledge and skills are in demand at home.”

– What helped TSU to win a MegaGrant?

“It is the experience in a very important and promising field of materials science. In Tomsk, titanium nickelide implants with a high rate of survival have been developed for 30 years. The main advantage of the implants is their biocompatibility with the human body. The contact of metal with biological tissue causes formation of different films, depending on the organic environment, and the cells grow into the metal implant. Thus, there is no rejection, the main problem to occur during damaged organ replacement.

Another very important positive feature: the alloy exhibits shape memory. It can be bent by heating to a certain temperature, and the metal remembers this shape. Then it is cooled, unbent again, in order to easier perform the operation and implant it into the human body, where, heated up to the body temperature, the metal takes its original shape. This occurs due to a reversible martensitic transformation in the material, when one crystal structure changes into another under temperature or deformation effects, and when external effects are removed, it returns to its original state.

In Tomsk, I succeeded to conduct a highly interesting experiment to test the superelastic properties of a wire with a diameter of 60 microns, the size of a human hair, obtained in the laboratory. The wire had to be strongly stretched, but not allowed to break. However, conventional equipment was not appropriate to study its mechanical and functional properties. We developed a portable device for stretching a thin wire and low-modulus materials, which has no analogues in the world. In Akademgorodok, a thermal chamber was used, and it was found that the wire heats up to about 37 degrees Celsius during stretching. The feature of this material is that it does not break, and it stretches like rubber. Titanium nickelide exhibits high wear resistance and biocompatibility; therefore, it can serve a person as an implant all his life, which cannot be said for proper titanium. One more, probably, the main thing: the TSU laboratory has learned how to make braided knitwear from wire, which is very soft and delicate to the touch. The laboratory also produces porous titanium nickelide by self-propagating high-temperature synthesis.”

– How does biocompatibility work? Why does not the human body perceive these materials as aliens?

“Answers to questions about what are films and how they are formed, as well as many other questions concerning the interaction of implants and human tissues, and their behavior under physiological stress, are the main fundamental task the grant sets to solve during these years. Based on the research results, we will publish several papers in the first quartile journals.”

– How can your materials be used? Will they be in demand?

“In Siberia, it has long been known that titanium nickelide can be used to make a wide variety of structures and to replace damaged organs. Usually it happens like this: a doctor comes to the laboratory and explains the problem of the patient and what kind of implant he needs. Together they decide how to help the human testing the metal biocompatibility in mice. Tomsk scientists have made a lot of successes. They made an experimental nickelide rib for a dog. A laboratory employee had part of the gums corroded by a cyst – there was practically nothing to fix the teeth on. Titanium nickelide powder restored the bone tissue – the teeth were preserved.

The materials are used for plastic surgery of cancer patients. Doctors remove cancerous tumors, apply a metal mesh and a piece of the patient’s healthy skin to the affected area, and they grow together! Once I was in Israel and met the head of the Department of Maxillofacial Surgery. For two years, he could not help a man whose face was disfigured by a bullet. The surgeon used different types of implants, but they did not survive due to insufficient biocompatibility. I told him about the features of titanium nickelide, and he became interested in the Russian development. In the Republic of Korea, implants made from this alloy are successfully used to restore the spine.

Titanium nickelide can be used to make different implants. Our task is to prove their safety and effectiveness, and, of course, to convince doctors: now, when they hear about titanium nickelide, their first reaction is distrust. After all, they are convinced that nickel is a toxic material. Although in fact, titanium is more dangerous. Yet, we have to confirm this.”

– Are there any analogues to your material?

“As far as I know, there are few papers on titanium nickelide biocompatibility – about 300. However, books have been published about it in Japan and the USA, so research in this area is underway. However, judging by the papers, they are trying to use the alloy not as an implant, but only as a shape memory material. It ought to be noted that the use of implants requires a lot of permits, and considerable financial investments should be made to bring them to the market. It is not surprising that I haven’t read about successful application of the implants in the literature so far. In my opinion, there are no analogues to our, I emphasize, universal material. This opens up ample opportunities for this material.”

– How much can implants cost?

“They can cost hundreds and thousands of dollars, because you need not only to get an adequate material, but also to make a product from it.”

– When will you next come in Tomsk?

“I will definitely come back in the summer. The laboratory renovation will be completed by then. It will be necessary to see about the purchase of equipment (we will definitely need an electron microscope). There are about 30–40 laboratory employees, including many young people, this topic attracts them. Our entire team is enthusiasts confident in the prospects of titanium nickelide.”

Author: Yury Drize.

Source:  Poisknews.